Electronic component

Abstract

The electronic component comprises: a functional element having an electrode; and a bus bar electrically and mechanically connected to the electrode. The bus bar includes a body and a connection conductor formed integrally with the body. The connection conductor has: a first arm and a second arm which are directly connected to the body; and a first connection part and a second connection part which correspond one-to-one to the first arm and the second arm, respectively, protrude from respective tips of the first arm and the second arm and are connected to the electrode by conductive members. Where A is the centre-to-centre distance between a portion connecting the body and the first arm and a portion connecting the body and the second arm, and B is the centre-to-centre distance between the first connection part and the second connection part, it holds that A > B when the coefficient of linear expansion of the functional element is larger than the coefficient of linear expansion of the bus bar.

Description

Electronic Components

[0001] The present disclosure relates generally to electronic components, and more particularly to electronic components including a functional element and a bus bar.

[0002] Patent Document 1 discloses a capacitor that includes a plurality of elements and a pair of bus bars.

[0003] Each of the plurality of elements has a flat shape consisting of a pair of flat portions and a pair of curved portions. Each of the plurality of elements has a pair of end electrodes on both ends. The plurality of elements are arranged in a row so that the pair of flat portions are located on the same plane or parallel planes.

[0004] Each of the pair of bus bars has an electrode connection portion connected to each end surface electrode of the plurality of elements and an external connection portion for electrically connecting the plurality of elements to the outside. The pair of bus bars is arranged along the arrangement direction of the plurality of elements.

[0005] JP 2013-089653 A

[0006] An electronic component according to one aspect of the present disclosure includes a functional element having an electrode and a busbar electrically and mechanically connected to the electrode. The busbar includes a main body and a connection conductor integrally formed with the main body. The connection conductor has a first arm and a second arm directly connected to the main body in a longitudinal direction, and a first connection portion and a second connection portion corresponding to the first arm and the second arm, respectively, protruding from the distal end of the first arm and the second arm, and connected to the electrode by a conductive member. When the center-to-center distance between a connection point between the main body and the first arm and a connection point between the main body and the second arm is A and the center-to-center distance between the first connection portion and the second connection portion is B, A>B holds when the linear expansion coefficient of the functional element is greater than the linear expansion coefficient of the busbar.

[0007] According to the present disclosure, warpage can be suppressed.

[0008] FIG. 1 is a front view showing a main portion of an electronic component according to this embodiment. FIG. 2 is a side view including an enlarged view of a portion of the electronic component. FIG. 3 is a perspective view of the electronic component. FIG. 4 is a perspective view of the electronic component viewed from a different angle than FIG. 3. FIG. 5 is a perspective view in which a portion of a functional element is exploded. FIG. 6 is an enlarged front view of a main portion of FIG. 1. FIG. 7A is a perspective view showing a first modified example of the electronic component. FIG. 7B is a plan view showing the first modified example of the electronic component. FIG. 7C is a cross-sectional view taken along line X-X of FIG. 7B. FIG. 8A is a perspective view showing a portion of the first modified example of the electronic component. FIG. 8B is a perspective view showing a portion of the first modified example of the electronic component viewed from a different angle than FIG. 8A. FIG. 9A is a diagram illustrating an estimated mechanism by which warpage occurs in a typical electronic component. FIG. 9B is a diagram illustrating an estimated mechanism by which warpage occurs in a typical electronic component. FIG. 10A is a front view showing a main portion of a second modified example of the electronic component. FIG. 10B is an enlarged front view of the main portion of FIG. 10A. FIG. 11A is a graph showing the relationship between the linear expansion coefficient of the functional element and the amount of warpage for Examples 1 to 4 and Comparative Example 1. FIG. 11B is a graph showing the relationship between the linear expansion coefficient of the busbar and the amount of warpage for Examples 5 to 8 and Comparative Example 2. FIG. 12A is a graph showing the relationship between the center-to-center distance B between two connection portions and the stress at the base of the arm portion (stress occurring at the connection point between the main body and the arm portion). FIG. 12B is a graph showing the relationship between the center-to-center distance B between two connection portions and the amount of warpage. FIG. 13A is a graph showing the relationship between the ratio (A / B) of the center-to-center distance A at the connection points between the main body and the two arm portions to the center-to-center distance B between the two connection portions and the amount of warpage. FIG. 13B is a graph showing the relationship between the angle θ formed by the line segment C connecting the connection points between the main body and the two arm portions and the extension direction of the arm portions and the amount of warpage.

[0009] The problems in the prior art will be briefly described below.

[0010] The capacitor described in Patent Document 1 has a problem in that warping easily occurs in the arrangement direction of the multiple elements when a thermal load is applied.

[0011] The present disclosure provides an electronic component that can suppress warpage.

[0012] 9A and 9B show an example of a general electronic component 1. This electronic component 1 includes a functional element 2 and a bus bar 3. The functional element 2 has an electrode 21. The bus bar 3 is electrically and mechanically connected to the electrode 21.

[0013] More specifically, the busbar 3 has a main body 30 and a plurality of connection portions 6. The main body 30 has a longitudinal direction D1. The plurality of connection portions 6 are formed directly on the main body 30 and extend in a direction D2 perpendicular to the longitudinal direction D1. Two connection portions 6 are electrically and mechanically connected to one functional element 2. The capacitor of Patent Document 1 also has a similar structure.

[0014] When a thermal load is applied to the electronic component 1, warping tends to occur in the arrangement direction (longitudinal direction D1) of the multiple functional elements 2, as shown in Figure 9B. The inventors conducted research to suppress this warping and found that one of the causes of the warping is the difference in the thermal properties (e.g., linear expansion coefficient) of the functional elements 2 and the busbar 3. Further research revealed that large stress tends to occur in the portion where the connection portion 6 and the main body portion 30 are connected (portion R in Figure 9A).

[0015] Based on the above, the inventors have hypothesized the mechanism by which warpage occurs in the electronic component 1 as follows. Specifically, when a thermal load is applied to the electronic component 1 (including when the functional element 2 itself generates heat due to current flow), the degree of thermal expansion of the functional element 2 (indicated by the double-headed arrow f2 in FIG. 9A ) differs from the degree of thermal expansion of the busbar 3 (indicated by the double-headed arrow f3 in FIG. 9A ), causing warpage in the functional element 2 (indicated by the double-headed arrow w2 in FIG. 9A ). In the electronic component 1 shown in FIGS. 9A and 9B , multiple functional elements 2 are arranged in the longitudinal direction D1, and thus the warpage occurring in each of the multiple functional elements 2 accumulates. As a result, the electronic component 1 as a whole warps in a bow-like shape, as indicated by the double-headed arrow w1 in FIG. 9A . Note that δ1 in FIG. 9B indicates the amount of warpage deformation occurring in the electronic component 1.

[0016] Based on the above-mentioned presumed mechanism, the inventors of the present invention have further pursued intensive research and have developed an electronic component 1 that can suppress warpage.

[0017] That is, in the electronic component 1 according to this embodiment, the bus bar 3 includes a connection conductor 33 (see FIGS. 1 and 10A). The connection conductor 33 is integrally formed with the main body 30. The connection conductor 33 further has two arm portions 8 and two connection portions 6. The two arm portions 8 are directly connected to the main body 30. The two connection portions 6 correspond one-to-one to the two arm portions 8. The two connection portions 6 protrude from the tips of the two arm portions 8. The two connection portions 6 are connected to the electrodes 21 by conductive members 60 (see FIG. 2).

[0018] As shown in Figures 6 and 10B, when the center-to-center distance between the connection points between the main body 30 and the two arm portions 8 is A and the center-to-center distance between the two connection portions 6 is B, if the linear expansion coefficient of the functional element 2 is greater than the linear expansion coefficient of the bus bar 3, then A > B holds.

[0019] 9A and 9B and the electronic component 1 according to this embodiment have in common the fact that two connection portions 6 are electrically and mechanically connected to one functional element 2. In this way, two connection portions 6, rather than one connection portion 6, are electrically and mechanically connected to one functional element 2, so that both of the above electronic components 1 can pass a high current and ensure the necessary current capacity.

[0020] 9A and 9B differ from the electronic component 1 according to this embodiment in the following respect. Specifically, in the electronic component 1 shown in FIGS. 9A and 9B , the center-to-center distance between the bases of the two connection portions 6 is equal to the center-to-center distance between the tips of the two connection portions 6. In contrast, in the electronic component 1 according to this embodiment, the center-to-center distance A between the bases of the two arm portions 8 is greater than the center-to-center distance B between the tips of the two connection portions 6. Therefore, even if stress occurs near the bases of the two arm portions 8 (the R portions in FIG. 1 ), the stress is easily alleviated.

[0021] Therefore, the electronic component 1 according to this embodiment can suppress warpage.

[0022] 2. Details The electronic component 1 according to this embodiment will be described below with reference to Figures 1 to 9B. Each figure is a schematic diagram, and the ratios of the sizes and thicknesses of the components in each figure do not necessarily reflect the actual dimensional ratios.

[0023] The arrows indicating each direction in each figure are not intended to define the direction of the electronic component 1 during use; they are merely depicted to facilitate understanding and have no substance. The first direction D1, second direction D2, and third direction D3 are mutually perpendicular. The first direction D1 is the longitudinal direction of the main body 30 of the busbar 3 and is sometimes referred to as the "left-right direction." One side of the first direction D1 means "left," and the other side of the first direction D1 means "right." The second direction D2 is the thickness direction (minor axis direction) of the functional element 2 and is sometimes referred to as the "up-down direction." One side of the second direction D2 means "up," and the other side of the second direction D2 means "down." The third direction D3 is the direction connecting two electrodes 21 of the functional element 2 and is sometimes referred to as the "front-rear direction." One side of the third direction D3 means "front," and the other side of the third direction D3 means "rear." A view along the first direction D1 is referred to as a side view. A view along the second direction D2 is referred to as a plan view. Viewing along the third direction D3 is called a front view.

[0024] 1 to 4 show an electronic component 1 according to this embodiment. The electronic component 1 includes a plurality of (four in this embodiment) functional elements 2 and a plurality of (two in this embodiment) bus bars 3. As shown in FIGS. 3 and 4, the four functional elements 2 are aligned in the left-right direction, and the two bus bars 3 are aligned in the front-rear direction.

[0025] <Functional Element> The functional element 2 is not particularly limited, but examples thereof include a passive element, an active element, etc. In this embodiment, the functional element 2 is a film capacitor element 27.

[0026] As shown in FIG. 5, the functional element 2 has an element body 20 and two electrodes 21 .

[0027] <Element Body> The element body 20 has a rounded rectangular shape in a front view and extends in the front-to-rear direction. The element body 20 has two end faces 22 and an outer circumferential surface 23. The two end faces 22 are a first end face 221 and a second end face 222. The first end face 221 is a surface facing forward, and the second end face 222 is a surface facing rearward. The outer circumferential surface 23 connects the first end face 221 and the second end face 222. Specifically, the outer circumferential surface 23 connects the outer circumferential edge of the first end face 221 to the outer circumferential edge of the second end face 222.

[0028] The element body 20 is formed by winding two metallized films 24. Specifically, the two metallized films 24 are wound around an axis parallel to the front-rear direction to form a cylindrical shape, and then pressed in the vertical direction to flatten, thereby obtaining the element body 20. As a result, the element body 20 has a major axis parallel to the left-right direction and a minor axis parallel to the up-down direction. The two metallized films 24 are a first metallized film 241 and a second metallized film 242.

[0029] The metallized film 24 includes a dielectric film 25 and a metal layer 26 .

[0030] Dielectric film 25 has a predetermined thickness and is elongated with a predetermined width in the front-to-rear direction. The thickness of dielectric film 25 is not particularly limited, but is, for example, 1 μm or more and 10 μm or less. The material of dielectric film 25 is not particularly limited, but examples thereof include polypropylene (PP) and polyethylene terephthalate (PET). Note that dielectric film 25 of first metallized film 241 is first dielectric film 251, and dielectric film 25 of second metallized film 242 is second dielectric film 252.

[0031] Metal layer 26 is provided on dielectric film 25. Specifically, metal layer 26 is formed on one side of dielectric film 25 by vapor deposition or the like. The material of metal layer 26 is not particularly limited, but examples thereof include aluminum (Al), magnesium (Mg), and alloys thereof. The thickness of metal layer 26 is not particularly limited, but is, for example, 5 nm to 100 nm. Note that metal layer 26 of first metalized film 241 is first metal layer 261, and metal layer 26 of second metalized film 242 is second metal layer 262. Inside element body 20, first metal layer 261 and second metal layer 262 face each other with dielectric film 25 interposed therebetween.

[0032] <Electrodes> The two electrodes 21 are formed on two end surfaces 22 of the element body 20 by metal spraying or the like. Specifically, the two electrodes 21 are a first electrode 211 and a second electrode 212, with the first electrode 211 formed on the first end surface 221 of the element body 20 and the second electrode 212 formed on the second end surface 222 of the element body 20. The material of the electrodes 21 is not particularly limited, but examples thereof include zinc (Zn), tin (Sn), and alloys thereof. The thickness of the electrodes 21 is not particularly limited, but is, for example, 0.5 mm or more and 1.5 mm or less.

[0033] The electrode 21 is electrically connected to the metal layer 26 inside the element body 20. Specifically, since the front edge of the first metal layer 261 is exposed at the first end surface 221 of the element body 20, the first electrode 211 is connected to the first metal layer 261. Note that the rear edge of the first metal layer 261 is not exposed at the second end surface 222 of the element body 20, so the first metal layer 261 is not connected to the second electrode 212. On the other hand, since the rear edge of the second metal layer 262 is exposed at the second end surface 222 of the element body 20, the second electrode 212 is connected to the second metal layer 262. Note that the front edge of the second metal layer 262 is not exposed at the first end surface 221 of the element body 20, so the second metal layer 262 is not connected to the first electrode 211.

[0034] <<Linear expansion coefficient>> The linear expansion coefficient of the functional element 2 is preferably 4.2 × 10 －５ / K or more 1.7×10－４ / K or less. In particular, it is preferable that the linear expansion coefficient in the left-right direction is in the above-mentioned range. It is also preferable that the linear expansion coefficient in the temperature range of from room temperature (e.g., 25°C) to 100°C is in the above-mentioned range. The linear expansion coefficient of the functional element 2 can be measured, for example, by the compression-expansion method of thermomechanical analysis (TMA).

[0035] <Busbar> The busbar 3 is a conductive member that is interposed between the functional element 2 and an external device (not shown) and is used to electrically connect the functional element 2 and the external device. The busbar 3 is formed by cutting a metal plate into a predetermined shape and then bending it appropriately. The metal plate is not particularly limited, but examples thereof include a copper plate and an aluminum plate.

[0036] In this embodiment, the two bus bars 3 are a first bus bar 31 and a second bus bar 32. Hereinafter, when simply referring to the bus bar 3, it means each of the first bus bar 31 and the second bus bar 32.

[0037] In the electronic component 1, the bus bar 3 is electrically and mechanically connected to the electrodes 21. The bus bar 3 includes a main body 30, a plurality of (four in this embodiment) connection conductors 33, and external connection terminals 34.

[0038] <<Main Body>> The main body 30 has a longitudinal direction D1. That is, the main body 30 is a portion extending in the left-right direction. Note that the main body 30 may or may not be in contact with the electrode 21, but is not directly fixed to the electrode 21.

[0039] <<Connection Conductor>> The connection conductor 33 is integrally formed with the main body portion 30. In this embodiment, the connection conductor 33 is formed on the lower side of the main body portion 30.

[0040] 3 and 4 , a plurality of (four in this embodiment) connection conductors 33 are connected one-to-one to a plurality of (four in this embodiment) functional elements 2. In this manner, one bus bar 3 is connected to a plurality of functional elements 2.

[0041] One connection conductor 33 has two arm portions 8 and two connection portions 6 .

[0042] [Arms] The two arms 8 are directly connected to the main body 30. The two arms 8 are a first arm 81 and a second arm 82.

[0043] The first arm 81 is linear and has a predetermined width, and is inclined with respect to the left-right direction. Specifically, the first arm 81 extends downward as it moves toward the right.

[0044] On the other hand, the second arm 82 is bilaterally symmetrical to the first arm 81. That is, the second arm 82 is also linear with a predetermined width and is inclined with respect to the left-right direction. However, the second arm 82 extends downward as it moves toward the left.

[0045] In this way, the center-to-center distance in the left-right direction between the first arm portion 81 and the second arm portion 82 decreases from top to bottom. Note that the center-to-center distance is the distance connecting the center of the width dimension of the first arm portion 81 in a direction perpendicular to the direction in which the first arm portion 81 extends and the center of the width dimension of the second arm portion 82 in a direction perpendicular to the direction in which the second arm portion 82 extends.

[0046] The two arms 8 may or may not be in contact with the electrode 21, but are not directly fixed to the electrode 21.

[0047] [Connection Portions] The two connection portions 6 correspond one-to-one to the two arm portions 8. Specifically, the two connection portions 6 are a first connection portion 61 and a second connection portion 62, and the first connection portion 61 corresponds to the first arm portion 81, and the second connection portion 62 corresponds to the second arm portion 82.

[0048] The two connection portions 6 protrude from the tips of the two arm portions 8. Specifically, the first connection portion 61 protrudes downward from the tip of the first arm portion 81, and the second connection portion 62 protrudes downward from the tip of the second arm portion 82.

[0049] 2, the two connection portions 6 are connected to the electrodes 21 by conductive members 60. Specifically, the connection portions 6 are placed on the electrodes 21, and the conductive members 60 are supplied from above, connecting the electrodes 21 and the connection portions 6 by the conductive members 60. The conductive members 60 are not particularly limited, but examples thereof include solder.

[0050] In this manner, the bus bar 3 is electrically and mechanically connected to the electrode 21 .

[0051] <External Connection Terminals> The external connection terminals 34 are terminals used to connect the electronic component 1 to an external device (not shown). The external connection terminals 34 are integrally formed with the main body 30. In this embodiment, the external connection terminals 34 are formed to protrude forward on both the first bus bar 31 and the second bus bar 32. However, an insulating plate 93 is interposed between the external connection terminals 34 of the first bus bar 31 and the external connection terminals 34 of the second bus bar 32, and the two external connection terminals 34 are electrically insulated from each other.

[0052] <<Linear expansion coefficient>> The linear expansion coefficient of the bus bar 3 is preferably 8.5 × 10 －６ / K or more 3.4×10 －５ / K or less. In particular, it is preferable that the linear expansion coefficient in the left-right direction is within the above-mentioned range. It is also preferable that the linear expansion coefficient in the temperature range of room temperature (e.g., 25°C) or higher and 100°C or lower is within the above-mentioned range. The linear expansion coefficient of the bus bar 3 can be measured, for example, by the compression-expansion method of thermomechanical analysis (TMA).

[0053] <Relational Expressions> Relational expressions that hold for the connecting conductor 33 of this embodiment will be described below with reference to FIG.

[0054] That is, in this embodiment, when the center-to-center distance between the connection points between the main body 30 and the two arm portions 8 is A and the center-to-center distance between the two connection portions 6 is B, and the linear expansion coefficient of the functional element 2 is greater than the linear expansion coefficient of the bus bar 3, A > B holds.

[0055] More specifically, the distance A above is the distance connecting the center of the width of the first arm 81 at the connection point between the main body 30 and the first arm 81 (the base of the first arm 81) and the center of the width of the second arm 82 at the connection point between the main body 30 and the second arm 82 (the base of the second arm 82). On the other hand, the distance B above is the distance connecting the center of the width of the first connection portion 61 in the direction perpendicular to the extension direction of the first connection portion 61 (the left-right direction) and the center of the width of the second connection portion 62 in the direction perpendicular to the extension direction of the second connection portion 62 (the left-right direction).

[0056] In this embodiment, the relationship 2.9≦A / B≦8.3 is preferably satisfied.

[0057] Furthermore, in this embodiment, if the line segment connecting the main body 30 and the connection points of the two arms 8 is defined as line segment C, the angle θ [deg] between line segment C and the direction E in which at least one of the two arms 8 extends satisfies 26.5≦θ≦60.

[0058] More specifically, the line segment C connects the center of the width of the first arm 81 at the connection point between the main body 30 and the first arm 81 (the base of the first arm 81) and the center of the width of the second arm 82 at the connection point between the main body 30 and the second arm 82 (the base of the second arm 82). The E represents the direction E1 in which the first arm 81 extends and / or the direction E2 in which the second arm 82 extends. The angle θ represents the angle θ1 between the line segment C and the direction E1 in which the first arm 81 extends and / or the angle θ2 between the line segment C and the direction E2 in which the second arm 82 extends. In this embodiment, the first arm 81 and the second arm 82 are bilaterally symmetrical, and therefore the angle θ1 and the angle θ2 are the same.

[0059] <Effects> In the electronic component 1 according to this embodiment, the linear expansion coefficient of the functional element 2 is larger than the linear expansion coefficient of the busbar 3. Therefore, even if the distance between two points on the electrode 21 of the functional element 2 and the distance between two points on the main body 30 of the busbar 3 are equal before a thermal load is applied to the electronic component 1, after the thermal load is applied to the electronic component 1, the distance between the two points on the electrode 21 of the functional element 2 becomes larger than the distance between the two points on the main body 30 of the busbar 3.

[0060] Therefore, in the electronic component 1 according to this embodiment, the center-to-center distance A between the bases of the two arm portions 8 is set to be greater than the center-to-center distance B between the tips of the two connection portions 6. Here, the bases of the two arm portions 8 are easily affected by the thermal properties of the bus bar 3, and the tips of the two connection portions 6 are easily affected by the thermal properties of the functional element 2. Therefore, when a thermal load is applied to the electronic component 1, although both A and B increase due to thermal expansion, the difference between them decreases. This reduces the stress generated near the bases of the two arm portions 8 (portions R in FIG. 1 ).

[0061] For the above reasons, this embodiment can reduce warpage of the electronic component 1. This can also improve the reliability of the connection between the functional element 2 and the bus bar 3 and the dimensional accuracy of the electronic component 1.

[0062] Furthermore, in the electronic component 1 according to this embodiment, it is preferable that 2.9≦A / B≦8.3 be satisfied, which can further suppress warpage of the electronic component 1 (see the "Examples" section for details).

[0063] 6, in the electronic component 1 according to this embodiment, the angle θ [deg] between the line segment C and the direction E in which the arm portion 8 extends preferably satisfies the relationship 26.5≦θ≦60. This makes it possible to further suppress warpage of the electronic component 1 (see the "Example" section for details).

[0064] Furthermore, in the electronic component 1 according to this embodiment, the functional element 2 is a film capacitor element 27. The film capacitor element 27 uses a plastic film as a dielectric and is subject to large thermal expansion and contraction. However, the electronic component 1 according to this embodiment employs a bus bar 3 in which a Y-shaped connecting conductor 33 is connected to the main body 30 via a coupling portion 5, so that the electronic component 1 according to this embodiment has high utility value even when the functional element 2 is a film capacitor element 27. When the functional element 2 is a film capacitor element 27, the electronic component 1 according to this embodiment is used, for example, as an inverter component for a hybrid electric vehicle (HEV).

[0065] In the electronic component 1 according to this embodiment, the linear expansion coefficient of the functional element 2 is 4.2×10 －５ / K or more 1.7×10 －４ / K or less, which can further suppress warping of the electronic component 1 (see the "Examples" section for details).

[0066] In the electronic component 1 according to this embodiment, the linear expansion coefficient of the bus bar 3 is 8.5×10 －６ / K or more 3.4×10 －５ / K or less, which can further suppress warping of the electronic component 1 (see the "Examples" section for details).

[0067] Furthermore, although the electronic component 1 according to this embodiment includes a plurality of functional elements 2, warpage can be suppressed even when only one functional element 2 is included.

[0068] 7A to 8B, an electronic component 1 according to a first modification of the present embodiment will be described. In this modification, the same components as those in the present embodiment will be denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0069] This modification differs from the present embodiment in that the electronic component 1 includes a sealing body 9. Furthermore, in this modification, the bus bar 3 includes the same connecting conductor 33 as in the present embodiment (see FIGS. 8A and 8B ), but differs from the present embodiment in that the external connection terminals 34 are formed to protrude upward.

[0070] The sealing body 9 includes a case 90 and a filling resin 91 .

[0071] The case 90 is open upward and accommodates a plurality of (four in this modification) functional elements 2 and a plurality of (two in this modification) bus bars 3 shown in Figures 8A and 8B.

[0072] The case 90 has attachment portions 92. The attachment portions 92 are used to attach the case 90 to an external device. In this modification, the attachment portions 92 are formed on both the left and right sides of the case 90.

[0073] The filling resin 91 is a resin that fills the inside of the case 90. The filling resin 91 is not particularly limited, but examples thereof include thermosetting resins such as epoxy resins.

[0074] In this manner, the sealing body 9 seals at least a portion of the bus bar 3 (in this modification, the portion excluding the external connection terminals 34) and the functional element 2. The external connection terminals 34 are exposed to the outside.

[0075] <Effects of the First Modification> In this modification, when at least a portion of the bus bar 3 and the functional element 2 are sealed with the sealing body 9, there is a possibility that a thermal load will be applied to the bus bar 3 and the functional element 2. However, in this modification as well, A>B holds, so warpage can be suppressed, for example, while the filled resin 91 changes from a liquid state to a gel state and then hardens. Moreover, because the functional element 2 and the bus bar 3 can be sealed in a state where warpage is suppressed, both residual stress and distortion can be reduced.

[0076] Next, an electronic component 1 according to a second modification of the present embodiment will be described with reference to Fig. 10A and Fig. 10B. In this modification, components similar to those in the present embodiment are denoted by the same reference numerals as in the present embodiment, and detailed description thereof may be omitted.

[0077] In this modification, the shape of the connecting conductor 33 is different from that of the connecting conductor 33 of this embodiment.

[0078] <Connection Conductor> In this modification, the two arms 8 are bent. The first arm 81 is bent in an L-shape. Specifically, the first arm 81 extends downward from the main body 30 and then extends to the right. The first connection portion 61 protrudes downward from the tip of the first arm 81.

[0079] On the other hand, the second arm 82 is bilaterally symmetrical to the first arm 81. That is, the second arm 82 is bent in an inverted L shape. Specifically, the second arm 82 extends downward from the main body 30 and then extends to the left. The second connection portion 62 protrudes downward from the tip of the second arm 82.

[0080] In this modified example, as in the present embodiment, when the center-to-center distance of the connection points between the main body 30 and the two arm portions 8 is A and the center-to-center distance of the two connection portions 6 is B, if the linear expansion coefficient of the functional element 2 is greater than the linear expansion coefficient of the bus bar 3, then A > B holds.

[0081] 10B , in this modification, the center-to-center distance A between the bases of the two arm portions 8 is set to be greater than the center-to-center distance B between the tips of the two connection portions 6. Therefore, in this modification, warping of the electronic component 1 can be reduced. This also improves the connection reliability between the functional element 2 and the bus bar 3 and the dimensional accuracy of the electronic component 1.

[0082] 3. Other Modifications In the present embodiment, the electronic component 1 includes a plurality of functional elements 2, but the electronic component 1 may include only one functional element 2.

[0083] In this embodiment, the functional element 2 is a film capacitor element 27, but is not limited to this. The functional element 2 may be, for example, a power choke coil or the like.

[0084] In this embodiment, the film capacitor element 27 is of a wound type, but may be of a laminated type, in which a plurality of metallized films 24 are laminated in one direction (for example, vertically).

[0085] In this embodiment, the bus bar 3 includes a plurality of connecting conductors 33, but the bus bar 3 may include only one connecting conductor 33.

[0086] 4. Aspects As is clear from the above-described embodiments and modifications, the present disclosure includes the following aspects. In the following, reference numerals are given in parentheses only to clarify the correspondence with the embodiments.

[0087] The first aspect is an electronic component (1) comprising a functional element (2) having an electrode (21) and a bus bar (3) electrically and mechanically connected to the electrode (21). The bus bar (3) includes a main body (30) and a connection conductor (33) formed integrally with the main body (30). The connection conductor (33) has a first arm (8) and a second arm (8) directly connected to the main body (30) in a longitudinal direction (D1), and a first connection portion (6) and a second connection portion (6) that correspond one-to-one to the first arm (8) and the second arm (8), protrude from the tip of the first arm (8) and the second arm (8), and are connected to the electrode (21) by a conductive member (60). When the center-to-center distance between the connection point between the main body portion (30) and the first arm portion (8) and the connection point between the main body portion (30) and the second arm portion (8) is A and the center-to-center distance between the connection point between the first connection portion (6) and the second connection portion (6) is B, and when the linear expansion coefficient of the functional element (2) is greater than the linear expansion coefficient of the bus bar (3), A > B holds.

[0088] According to this aspect, warping can be suppressed.

[0089] The second aspect is an electronic component (1) based on the first aspect. In the second aspect, 2.9≦A / B≦8.3 is satisfied.

[0090] According to this aspect, warping can be further suppressed.

[0091] A third aspect is an electronic component (1) based on the first or second aspect. In the third aspect, when a line segment connecting the connection point between the main body (30) and the first arm portion and the connection point between the main body (30) and the second arm portion (8) is defined as a line segment C, and an angle formed by the line segment C and a direction (E) in which one of the first arm portion and the second arm portion (8) extends is defined as θ [deg], 26.5≦θ≦60 holds.

[0092] According to this aspect, warping can be further suppressed.

[0093] A fourth aspect is an electronic component (1) based on any one of the first to third aspects, further comprising a seal (9) that seals at least a portion of the bus bar (3) and the functional element (2).

[0094] According to this aspect, warping can be further suppressed.

[0095] A fifth aspect is an electronic component (1) based on any one of the first to fourth aspects. In the fifth aspect, the functional element (2) is a film capacitor element (27) configured by winding or laminating a metallized film (24). The metallized film (24) has a dielectric film (25) and a metal layer (26) provided on the dielectric film (25) and electrically connected to the electrode (21).

[0096] According to this aspect, warping can be further suppressed.

[0097] A sixth aspect is an electronic component (1) based on any one of the first to fifth aspects. In the sixth aspect, the linear expansion coefficient of the functional element (2) is 4.2×10 －５ / K or more 1.7×10 －４ / K or less.

[0098] According to this aspect, warping can be further suppressed.

[0099] A seventh aspect is an electronic component (1) based on any one of the first to sixth aspects. In the seventh aspect, the linear expansion coefficient of the bus bar (3) is 8.5×10 －６ / K or more 3.4×10 －５ / K or less.

[0100] According to this aspect, warping can be further suppressed.

[0101] An eighth aspect is an electronic component (1) based on any one of the first to seventh aspects. In the eighth aspect, the electronic component (1) includes a plurality of the functional elements (2). The bus bar (3) includes a plurality of the connecting conductors (33). The plurality of functional elements (2) and the plurality of connecting conductors (33) are connected in a one-to-one relationship.

[0102] According to this aspect, warping can be further suppressed.

[0103] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to the following examples.

[0104] Examples 1 to 8 (e1 to e8) An analytical model of the electronic component 1 shown in FIG. 3 was created for each of Examples 1 to 8 (e1 to e8). Three analytical models were created for each of the eight types of Examples 1 to 8 (e1 to e8), for a total of 24 types. These 24 types differ in the combination of the center-to-center distance B between the two connection portions 6, the linear expansion coefficient of the functional element 2, and the linear expansion coefficient of the busbar 3. The analytical models for Example 1 (e1) were designated e1(a), e1(b), and e1(c). The analytical models for Example 2 (e2) were designated e2(a), e2(b), and e2(c). The analytical models for Example 3 (e3) were designated e3(a), e3(b), and e3(c). Additionally, the analytical models for Example 4 (e4) were designated e4(a), e4(b), and e4(c). The analytical models of Example 5 were designated e5(d), e5(e), and e5(f). The analytical models of Example 6 were designated e6(d), e6(e), and e6(f). The analytical models of Example 7 were designated e7(d), e7(e), and e7(f). The analytical models of Example 8 were designated e8(d), e8(e), and e8(f) (see Tables 1 and 2). An example of the size of electronic component 1 is a total length (longitudinal direction) of 60 mm, a total width (depth direction = electrode direction) of 40 mm, and a total height (transverse direction) of 30 mm.

[0105] That is, in the three types of Example 1, e1(a), e1(b), and e1(c), as shown in Table 1, the center-to-center distance B of the two connecting portions 6 is constant, the linear expansion coefficient of the bus bar 3 is constant, and the linear expansion coefficient of the functional element 2 is changed. The same applies to Examples 2 to 4 (e2 to e4).

[0106] On the other hand, in the three types of Example 5, e5(d), e5(e), and e5(f), as shown in Table 2, the center-to-center distance B of the two connecting portions 6 is constant, the linear expansion coefficient of the functional element 2 is constant, and the linear expansion coefficient of the bus bar 3 is changed. The same applies to Examples 6 to 8 (e6 to e8).

[0107] <Comparative Examples 1 and 2 (c1, c2)> For each of Comparative Examples 1 and 2 (c1, c2), an analytical model of the electronic component 1 shown in FIG. 9B was created. Three analytical models were created for Comparative Example 1 (c1) and three for Comparative Example 2 (c2), for a total of six analytical models. These models were designated c1(a), c1(b), c1(c) and c2(d), and c2(e) and c2(f), respectively (see Tables 1 and 2). The electronic components 1 of Comparative Examples 1 and 2 (c1, c2) were identical to the electronic components 1 of Examples 1 to 8 (e1 to e8), except that, instead of the connection conductors 33 of the electronic components 1 of Examples 1 to 8 (e1 to e8), two connection portions 6 protruded directly downward from the main body 30 of the busbar 3.

[0108] As shown in Table 1, the three types of comparative example 1, c1(a), c1(b), and c1(c), have a constant center-to-center distance B between the two connection portions 6, a constant linear expansion coefficient of the bus bar 3, and different linear expansion coefficients of the functional element 2.

[0109] On the other hand, in the three types of comparative example 2, c2(d), c2(e), and c2(f), as shown in Table 2, the center-to-center distance B of the two connection portions 6 is constant, and the linear expansion coefficient of the functional element 2 is constant, while the linear expansion coefficient of the bus bar 3 is changed.

[0110] <Evaluation> Using analytical models of the electronic components 1 of Examples 1 to 4 (e1 to e4) and Comparative Example 1 (c1), CAE (Computer Aided Engineering) analysis was performed to evaluate the amount of warpage deformation of each electronic component 1. Under the conditions of the CAE analysis, the ambient temperature was increased from 25°C to 85°C. The results are shown in Table 1. Table 1 is graphed in FIG. 11A.

[0111]

[0112] Here, the amount of warpage deformation means the amount of warpage deformation (δ1) of the electronic component 1 with respect to the arrangement direction (first direction D1) of the plurality of functional elements 2, as shown in FIG. 9B.

[0113] 11A, it can be seen that the smaller the linear expansion coefficient of the functional element 2, the smaller the amount of warpage. Furthermore, it can be seen that if the linear expansion coefficient of the functional element 2 is the same, the shorter the center-to-center distance B of the two connecting portions 6, the smaller the amount of warpage.

[0114] Meanwhile, CAE analysis was performed under the same conditions as above using analytical models of electronic components 1 of Examples 5 to 8 (e5 to e8) and Comparative Example 2 (c2), to evaluate the amount of warpage deformation of each electronic component 1. The results are shown in Table 2. Table 2 is graphed in FIG. 11B.

[0115]

[0116] From Table 2 and FIG. 11B, it can be seen that, if the linear expansion coefficient of the bus bar 3 is the same, the shorter the center-to-center distance B between the two connection portions 6, the smaller the amount of warpage deformation.

[0117] Next, the stress at the base of the arm (stress occurring at the connection point between the main body and the arm) was evaluated for Examples 1 to 4 (specifically, e1(b), e2(b), e3(b), and e4(b)). The results are shown in Figure 12A. Similar results were obtained for Examples 5 to 8 (specifically, e5(b), e6(b), e7(b), and e8(b)).

[0118] It can be seen from FIG. 12A that the stress at the base of the arm portion 8 decreases as the center-to-center distance B between the two connecting portions 6 decreases.

[0119] Table 3 is shown below. Table 3 summarizes the center-to-center distance B between the two connecting portions 6, the amount of warpage deformation, and the warpage improvement rate for Comparative Example 1 (specifically, c1(b)) and Examples 1 to 4 (specifically, e1(b), e2(b), e3(b), and e4(b)). FIG. 12B is a graph of Table 3. Similar results were obtained for Comparative Example 2 (specifically, c2(e)) and Examples 5 to 8 (specifically, e5(b), e6(b), e7(b), and e8(b)).

[0120]

[0121] Here, the warpage improvement rate (%) was calculated by the following formula (1).

[0122]

[0123] 12B, it can be seen that the shorter the center-to-center distance B between the two connecting portions 6, the smaller the amount of warpage deformation. It can also be seen that the shorter the center-to-center distance B between the two connecting portions 6, the greater the warpage improvement rate.

[0124] Table 4 is shown below. Table 4 summarizes the ratio (A / B) of the center-to-center distance A of the connection points between the main body 30 and the two arm portions 8 to the center-to-center distance B of the two connection portions 6, and the amount of warpage deformation, for Comparative Example 1 (specifically, c1(b)) and Examples 1 to 4 (specifically, e1(b), e2(b), e3(b), and e4(b)). FIG. 13A is a graph of Table 4. Similar results were obtained for Comparative Example 2 (specifically, c2(e)) and Examples 5 to 8 (specifically, e5(b), e6(b), e7(b), and e8(b)).

[0125]

[0126] From Table 4 and FIG. 13A, it can be seen that the smaller the A / B ratio, the smaller the amount of warpage deformation.

[0127] Table 5 is shown next. Table 5 summarizes the angle θ formed between the line segment C connecting the connection points between the main body 30 and the two arm portions 8 and the direction E in which the arm portions 8 extend, as well as the amount of warpage deformation, for Comparative Example 1 (specifically, c1(b)) and Examples 1 to 4 (specifically, e1(b), e2(b), e3(b), and e4(b)). FIG. 13B is a graph of Table 5. Similar results were obtained for Comparative Example 2 (specifically, c2(e)) and Examples 5 to 8 (specifically, e5(b), e6(b), e7(b), and e8(b)).

[0128]

[0129] From Table 5 and FIG. 13B, it can be seen that the smaller the angle θ of the arm portion 8, the smaller the amount of warpage deformation.

[0130] REFERENCE SIGNS LIST 1 Electronic component 2 Functional element 21 Electrode 24 Metallized film 25 Dielectric film 26 Metal layer 3 Bus bar 30 Main body 33 Connection conductor 6 Connection portion 60 Conductive member 8 Arm portion 9 Sealing body D1 First direction (longitudinal direction) E Direction in which arm portion extends

Claims

1. An electronic component comprising: a functional element having an electrode; and a bus bar electrically and mechanically connected to the electrode, the bus bar including a main body and a connecting conductor formed integrally with the main body, the connecting conductor having a first arm and a second arm directly connected to the main body, and a first connection portion and a second connection portion that correspond one-to-one to the first arm and the second arm, protrude from the tip of the first arm and the second arm, and are connected to the electrode by a conductive member, wherein A is the center-to-center distance between a connection point between the main body and the first arm and a connection point between the main body and the second arm, and B is the center-to-center distance between the first connection portion and the second connection portion, and when the linear expansion coefficient of the functional element is greater than the linear expansion coefficient of the bus bar, A>B holds.

2. The electronic component according to claim 1, wherein 2.9≦A / B≦8.3 holds true.

3. An electronic component as claimed in claim 1 or 2, wherein, when a line segment connecting the connection point between said main body and said first arm and the connection point between said main body and said second arm is defined as line segment C, and an angle between said line segment C and a direction in which one of said first arm and said second arm extends is defined as θ [deg], 26.5≦θ≦60 holds true.

4. The electronic component according to any one of claims 1 to 3, further comprising a sealant that seals at least a portion of the bus bar and the functional element.

5. The electronic component according to any one of claims 1 to 4, wherein the functional element is a film capacitor element formed by winding or laminating a metallized film, and the metallized film has a dielectric film and a metal layer provided on the dielectric film and electrically connected to the electrode.

6. The linear expansion coefficient of the functional element is 4.2×10 －５ / K or more 1.7×10 －４ The electronic component according to any one of claims 1 to 5, wherein the resistance is 0.1 to 0.5 μm.

7. The linear expansion coefficient of the bus bar is 8.5 x 10 －６ / K or more 3.4×10 －５ The electronic component according to claim 1 , wherein the resistance is 0.1 to 0.5 μm.

8. An electronic component according to any one of claims 1 to 7, comprising a plurality of functional elements including the functional element, the bus bar including a plurality of connecting conductors including a plurality of the connecting conductors, and the plurality of functional elements and the plurality of connecting conductors are connected in a one-to-one relationship.

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